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Early detection right at epidemic areas can prevent infectious diseases from propagation. Currently, the most common nucleic acid test—polymerase chain reaction (PCR) is time-consuming, complex, expensive and thermocycler required, thus limiting its utility in poor laboratory conditions or even non-laboratory condition of epidemic areas. Loop-mediated isothermal amplification (LAMP) is quick, cheap, sensitive and isothermal assay could be combined with a simple DNA extraction method to integrate into Lab-on-a-chip (LOC) device. Here, we attempted to improve LAMP method for malaria diagnosis on portable microfluidics chip platform by optimizing DNA extraction using boil and spin method and altering Tris-containing amplification buffer for ascertaining changing in pH of reaction solution. Basically, blood sample was mixed with extraction buffer containing Sodium Dedocyl Sulfate (SDS) concentration and treated under high temperature condition. Four concentrations of SDS (0, 0.4, 0.8 and 1%) were tested along with different temperature (65 and 95 °C) to adapt into LOC platform and avoid denaturation of LAMP reagent. All samples treated at 65 °C showed the presence of DNA after extraction. Furthermore, DNA amplification buffer was minimized Tris concentration to facilitate result read-out step. The releasing of hydrogen ion from amplification reaction causes increasing in pH which could be recognized by color of pH indicator paper or dye, for example, phenolphthalein. Throughout a series of experiments, LAMP is demonstrated that it can also occur in low-Tris buffer with pH indicator dye, efficiently. The positive sample will have a change from pink to transparent in solution color, otherwise, the negative sample will maintain pink. These improvements allowed us to adapt LAMP technique into Point-of-care (POC) devices in which the whole process run under isothermal condition (65 °C) and non-instrument required visual detection. The LAMP microfluidics chip will be potential tool for early detection infectious diseases and several other diseases in non-laboratory condition.

Summary Background A substantial proportion of Plasmodium species infections are asymptomatic with densities too low to be detectable with standard diagnostic techniques. The importance of such asymptomatic plasmodium infections in malaria transmission is probably related to their duration and density. To explore the duration of asymptomatic plasmodium infections and changes in parasite densities over time, a cohort of participants who were infected with Plasmodium parasites was observed over a 2-year follow-up period. Methods In this open cohort study, inhabitants of four villages in Vietnam were invited to participate in baseline and subsequent 3-monthly surveys up to 24 months, which included the collection of venous blood samples. Samples were batch-screened using ultra-sensitive (u)PCR (lower limit of detection of 22 parasites per mL). Participants found to be infected by uPCR during any of these surveys were invited to join a prospective cohort and provide monthly blood samples. We estimated the persistence of Plasmodium falciparum and Plasmodium vivax infections and changes in parasite densities over a study period of 24 months. Findings Between Dec 1, 2013, and Jan 8, 2016, 356 villagers participated in between one and 22 surveys. These study participants underwent 4248 uPCR evaluations (11·9 tests per participant). 1874 (32%) of 4248 uPCR tests indicated a plasmodium infection; 679 (36%) of 1874 tests were P falciparum monoinfections, 507 (27%) were P vivax monoinfections, 463 (25%) were co-infections with P falciparum and P vivax , and 225 (12%) were indeterminate species of Plasmodium . The median duration of P falciparum infection was 2 months (IQR 1–3); after accounting for censoring, participants had a 20% chance of having parasitaemia for 4 months or longer. The median duration of P vivax infection was 6 months (3–9), and participants had a 59% chance of having parasitaemia for 4 months or longer. The parasite densities of persistent infections oscillated; following ultralow-density infections, high-density infections developed frequently. Interpretation Persistent largely asymptomatic P vivax and P falciparum infections are common in this area of low seasonal malaria transmission. Infections with low-density parasitaemias can develop into much higher density infections at a later time, which are likely to sustain malaria endemicity. Funding The Wellcome Trust, Bill & Melinda Gates Foundation.

Background: Toxocariasis is a prevalent zoonosis disease caused by the closely related nematode species Toxocara canis and Toxocara cati which parasitise Canidae and Felidae respectively. In paratenic hosts, larvae of these worms cause multiple organ damage. However, how these paratenic hosts response to these worms and whether any common biomarker can be applied for diagnosis are still unclear. Methods: Excreted/secreted (E/S) antigens were prepared by culture of T. canis larvae in vitro. Using a western blot (WB) assay the humoral IgG responses, induced by Toxocara spp. larvae to the worm’s E/S antigens in different infected hosts including mice, rabbits and human, were examined. Results: In a mouse model of toxocariasis, intraperitoneal injection of T. canis larvae induces inflammatory leukocyte accumulation in the liver and the lungs but not in the brain, although a remarkable number of larvae were detected in this organ. Mice and rabbits responded differently to Toxocara spp. resulting in distinct heterogenous WB band patterns. Mice and rabbits both responded to a 33.1 kDa E/S constituent that turned out to be the most sensitive protein for serodiagnosis. Sera from human toxocariasis patients showed heterogenous WB band patterns similar to those observed in rabbits and all responded to the 33.1 kDa band. Conclusion: 33.1 kDa E/S protein can be considered as a critical common biomarker for toxocariasis immuno-diagnosis in both paratenic animals and human and its specificity requires further investigation.